This invention deals with a hold down device for multiple layered roofs, a device for detecting leaks in a roof, and a method of detecting leaks in a roof.
More specifically, there is provided a means for holding a multiple layered roof in a secure manner, with the additional benefit that the hold down devices utilized for such a purpose are adapted to function as water leak detectors.
Large industrial and commercial buildings quite typically have flat or near flat roof surfaces. These roof surfaces generally are multi-layered, that is they generally have in combination a roof supporting structure which is surmounted by a deck, and various layers of water impermeable membranes, thermal insulation and a ballast layer to assist in holding the entire roof from being blown away.
These types of roofs tend to be economical and function quite well as long as there is no break in the water-impermeable membrane. Once the water-impermeable membrane is broken, water enters the roof deck and seeps and runs and eventually enters the interior of the building. When this happens, the roof must be repaired, but often, one cannot detect where the membrane is broken and hence cannot effectively undertake repairs.
A second problem with the multiple layered roof is the inability of modern science to devise a scheme for holding the roofs in place, especially during violent storms accompanied by high winds. Current acceptable methods for holding down roofs are to cover the multiple layers with gravel or stone, point attachment, or a combination of both. This obviously tends to hold the roof down but such ballast contributes to the weight of the roof and requires strong structural support which results in higher costs for installation of such a roof.
It would be desirable to have a system for holding down roofs that would have the benefit of lowering the costs of the installation of such roofs. It would be a further benefit if the system used to hold down the roof could act as a more or less permanent system to detect leaks in the roof.
Several systems are currently in use for detecting leaks in a roof, for example, Gustafson, in U.S. Pat. No. 3,824,460, issued July 16, 1974, discloses a leakage sensor strip which is a pair of encased wires held essentially parallel to each other by a plurality of spaced webs which are an extension of the casing of the wires. The sensor strip is placed and held flat on a floor or roof deck over a certain length so that leakage anywhere along the probe will result in a capacitance change which can be sensed. It is important to note that this system does not provide a hold down function and furthermore, this sensor strip requires a metal channel over its full length in order to hold it flat on the surface. This feature renders the method of installing very expensive and time consuming.
Another patent, U.S. Pat. No. 3,967,197, discloses a method of detecting moisture in a multilayered roof system. The method disclosed consists of reading the capacitance at various predetermined points on a roof surface to create a base line reading and then periodically re-reading the capacitance at these same points to determine a deviation from the original reading. A capacitance meter is moved over the surface of the roof. Wherever the moisture in the roof has increased, the dielectric constant increases and the expectation is that this is indicative of a water leak.
A third system that has been used for detecting water leaks in a roof is that disclosed in U.S. Pat. No. 4,110,945, issued Sept. 5, 1978. In that method, a plurality of water detectors are positioned under the water-impermeable membrane of a roof. In the event that the water-impermeable membrane is broken and the roof leaks, the general area of the leak can be determined. Each such water detector is electrically powered and connected to a sensor at a location remote from the roof.
It should be noted that there is no hold down function in either the latter two systems and further, it should be noted that if the system of U.S. Pat. No. 4,110,945 requires repair, it may be required to remove and replace a fair section of the roof.
In spite of the usefulness of the above noted systems, there is still a need for a device for conveniently holding down roofs, and a need for a simpler, more dependable means of detecting roof leaks.